Texas & Pacific 4-4-2 "Atlantic" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class E-1 (Locobase 16387)

Data from "Texas & Pacific 4-4-2", Railway & Locomotive Engineering, Volume , No 8 (August 1906), pp. 371-372; and "Roster of Steam Locomotives of the Texas & Pacific" from Don Watson and Steve Brown, From Ox-Teams to Eagles (Cheltenham, Ontario, Canada: Boston Mills Press, 1978), Note F at the end of the roster. (Many thanks to Chris Hohl for his extensive research and his 3 December 2018 email, spreadsheet, and article link.)

Although only two in number and home-built (Allen Stanley suggested these were rebuilt from earlier 4-4-0s), these Atlantics followed the lines of the classic express locomotive in many respects. Although the boiler was relatively small in relation to the cylinders, the firebox ratios stood almost squarely in the middle of the more than 100 designs examined in this comparison. And a look at the profile shows large-diameter trailing wheels (51") under the firebox.

T&P's superintendent of motive power and rolling stock J W Addis supplied the R&LE with photos and specifications. Addis's saturated boiler was pressed to an unusually high 220 psi, which arrived in the cylinders through slide valves.

Unfortunately, says Drury (1993) "They turned out to be rear-heavy and unstable, and their 28,000 lb of tractive effort was no more than that of the considerably lighter D-9 Ten-Wheelers that preceded them." Watson & Brown provided more detail. The E-1s "could handle a good string of wooden coaches, but steel was to[o] much for them, they just couldn't pull many. " In sum, they say, "Typical of an Atlantic type locomotive they could run like hell, but couldn't move a setting hen."

Delivered as saturated-steam engines in 1906, they were superheated in 1917; see Locobase 8494.

Class E-1-s (Locobase 8494)

Data from T&P 1 - 1950ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Delivered as saturated-steam engines in 1906 (Locobase 16387), these homebuilts soon showed themselves to be tail-heavy and somewhat underpowered.

So the pair were completely made over in 1917. which time they were fitted with 14" piston valves and Southern valve gear. Boiler pressure decreased 35 psi (2.4 bar), but a simultaneous 4" (102 mm) reduction in driver diameter more than compensated and tractive effort increased.

The two changes may have improved locomotive ride and decreased maintenance demands. Moreover, combined heating surface area increased because the shops fitted the engines with a relatively large superheater. Another change was a conversion to oil burning.

Thus equipped, they served the T & P for another decade. The E-1-s were scrapped in December 1928 and January 1929, respectively.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID16,387 8494
RailroadTexas & Pacific (T&P)Texas & Pacific (T&P)
Number in Class22
Road Numbers339-340339-340
Number Built22
BuilderTexas & PacificTexas & Pacific
Valve GearStephensonSouthern
Locomotive Length and Weight
Driver Wheelbase (ft / m)7 / 2.137 / 2.13
Engine Wheelbase (ft / m)27.58 / 8.4127.58 / 8.41
Ratio of driving wheelbase to overall engine wheebase 0.25 0.25
Overall Wheelbase (engine & tender) (ft / m)56.87 / 17.3356.87 / 17.33
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)116,000 / 52,617123,986 / 56,239
Engine Weight (lbs / kg)204,000 / 92,533213,986 / 97,063
Tender Loaded Weight (lbs / kg)132,000 / 59,874114,879 / 52,108
Total Engine and Tender Weight (lbs / kg)336,000 / 152,407328,865 / 149,171
Tender Water Capacity (gals / ML)6500 / 24.626500 / 24.62
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.103000 / 11.40
Minimum weight of rail (calculated) (lb/yd / kg/m)97 / 48.50103 / 51.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)79 / 200775 / 1905
Boiler Pressure (psi / kPa)220 / 15.20185 / 12.80
High Pressure Cylinders (dia x stroke) (in / mm)20" x 28" / 508x71122" x 28" / 559x711
Tractive Effort (lbs / kg)26,511 / 12025.2028,414 / 12888.39
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.38 4.36
Heating Ability
Firebox Area (sq ft / m2)160 / 14.86180 / 16.72
Grate Area (sq ft / m2)45.30 / 4.2145 / 4.18
Evaporative Heating Surface (sq ft / m2)2891 / 268.582470 / 229.47
Superheating Surface (sq ft / m2)525 / 48.77
Combined Heating Surface (sq ft / m2)2891 / 268.582995 / 278.24
Evaporative Heating Surface/Cylinder Volume283.96200.50
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation99668325
Same as above plus superheater percentage99669824
Same as above but substitute firebox area for grate area35,20039,294
Power L110,50115,196
Power MT399.15540.41

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